1. Technical Field
The present invention relates to a novel acryl-base polymer film useful as optical members of liquid-crystal display devices, etc., to a novel optical compensation film for IPS or FFS-mode liquid-crystal display devices, and to an IPS or FFS-mode liquid-crystal display device having the film.
2. Background Art
Heretofore, in-plane switching (IPS) mode and fringe-field switching (FFS) mode liquid-crystal display devices have been proposed, where liquid-crystal molecules act to switch in a horizontal alignment state relative to the substrate, and in fact, they have been put into practical use. IPS-mode and FFS-mode liquid-crystal display devices are excellent in the viewing angle characteristics but have a problem of light leakage in oblique directions in the black state.
To overcome the problem of light leakage in oblique directions in the black state, proposed is use of a cellulose acylate film satisfying predetermined optical characteristics, as a protective film for the polarizing plate to be proposed between the liquid-crystal cell and the polarizing element (JP-A 2006-227606). Also proposed is disposition of a C-plate and a biaxial film between the liquid-crystal cell and the polarizing element (JP-A 2005-265889).
As an IPS-mode liquid-crystal display device having solved a problem of visibility failure owing to light leakage, color unevenness, color shift and the like around frames, proposed are use of a protective film having predetermined optical characteristics for the protective film of the polarizing plate to be disposed on the side of the liquid-crystal cell, and use of an acryl-base polymer film as one example of the protective film (JP-A 2007-264534).
On the other hand, JP-A 2007-38646 proposes a method of producing an optical film whose optical axis is inclined in the thickness direction by having a melt of thermoplastic polymer composition through the nip between two rolls running at a certain condition.